Cloud computing is an information technology (IT) paradigm that achieves coherence and scalability through the sharing of computing resources. One specific approach to cloud computing is software defined networking (SDN), which consolidates the network intelligence in a centralized network component. This is accomplished by decoupling the data plane (i.e., the data packet forwarding process) and the control plane (i.e., the packet routing process), and implementing the control plane in an SDN controller that is directly programmable. The SDN controller manages the network, with multiple connections to the physical, logical, and virtual resources.
In some SDN implementations, secondary SDN controller(s) may be deployed to serve as a backup in the event of a failure of the primary SDN controller.